The beleaguered administrators at Cooper Union have brought in private eye Bo Dietl to deal with the protesters who flooded a four-story staircase in December with 2,100 pingpong balls.

The students — who also staged a monthlong sit-in in president Jamshed Bharucha’s office — are upset with his plan to start charging tuition for the first time since the college was founded in 1859. The plan goes into effect this semester.

Dietl, seen lately in TV commercials for Arby’s, told me he is honored to provide security for the college, and said, “You have to take every threat seriously.”